1. Technical Field
The present disclosure relates to a solar cell and a solar cell module.
2. Description of the Related Art
Hybrid solar cells having a heterojunction structure of a crystalline semiconductor substrate and an amorphous semiconductor thin film are in practical use.
Patent Literature (PTL) 1 (Japanese Unexamined Patent Application Publication No. 2003-324209) discloses a photovoltaic device which improves interface characteristics between a crystalline semiconductor substrate and an amorphous semiconductor thin film to improve photoelectric conversion characteristics. Specifically, in the photovoltaic device disclosed by PTL 1, a p-type amorphous silicon thin film is laminated above a first principal surface of an n-type single-crystal silicon substrate with a first i-type amorphous silicon thin film being between the n-type single-crystal silicon substrate and the p-type amorphous silicon thin film. On the other hand, an n-type amorphous silicon thin film is laminated above a second principal surface of the n-type single-crystal silicon substrate with a second i-type amorphous silicon thin film being between the n-type single-crystal silicon substrate and the n-type amorphous silicon thin film. In the above configuration, after the second principal surface of the single-crystal silicon substrate is plasma-treated by plasma discharge using a mixed gas of a hydrogen gas and a gas including phosphorus on the second principal surface of the single-crystal silicon substrate, the second i-type amorphous silicon layer is formed. With this, phosphorus is introduced into an interface between the single-crystal silicon substrate and the second i-type amorphous silicon layer.
The above configuration makes it possible to reduce recombination of charge carriers in a semiconductor junction interface between the crystalline semiconductor substrate and the amorphous semiconductor thin film, improve junction characteristics, and to improve the photoelectric conversion characteristics of open-circuit voltage (Voc) etc.